3, 4-methylenedioxyphenyl acetals as synergists for pyrethrins



U ed tates P tent 3,4-METHYLENEDIOXYPHENYL ACETALS AS SYNERGISTS FOR PYRETHRINS Morton Beroza, Greenbelt, Md., assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Application June 15, 1955 Serial No. 515,798

3 (Cl. 260-3405) (Granted under Title 35, U. S. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to new compounds, namely, 3,4- methyenedioxyphenyl acetals, and to the processes for their preparation. The invention relates further to insecticidal compositions containing pyrethrins or pyrethrintype compounds and these new 3,4-methylenedioxyphenyl acetals as synergists therefor.

Pyrethrins and pyrethrin-type compounds, such as allethrin, are very useful due to their quick paralyzing or knockdown action on flies, gnats, mosquitoes, and the like. In use, they are generally mixed with inert carriers in low concentrations because of their high cost. In many cases a synergist is added. Such synergists have little or no insecticidal property in themselves but increase the action of the pyrethrins or pyrethrin-type compounds and thereby effect a saving in the use of these expensive materials.

According to the invention, there are provided 3,4- methylenedioxyphenyl acetals having the general formula g o-z C a wherein Z is a radical selected from the group consisting of 0 43 oH, (11H: H:

forming heterocyclic-type acetals, or CI -IR OR in which R is a member selected from the group consisting of hydrogen and a methyl radical, and R is a member selected from the group consisting of an alkyl radical containing 2 to 8 carbon atoms, such as ethyl, n-butyl, isobutyl, and 2-ethylhexyl, alkoxyethyl and alkoxyethoxyethyl radicals wherein the alkoxy group contains 1 to 4 carbon atoms, such as 2-methoxyethyl, 2-n-butoxyethyl, 2-(2-n-cthoxyethoxy)ethyl, and 2-(2-n-butoxyethoxy)- 2,832,792 Patented Apr. 29, 1958 ethyl, a chloroethyl radical, such as 2-chloroethyl, and a 3,4-methylenedioxyphenyl radical.

Most of these acetals are prepared from vinyl others by the following method: 2 ii Any peroxides in the vinyl ethyl, as, for example, those which might have formed in the ether upon standing in light, are first destroyed with an alkaline reducing agent, such as sodium sulfite. The ether is then distilled .to remove any stabilizer which may be present therein, as, for example, di-Z-ethylhexylamine. A small drop of a mineral acid catalyst such as concentratedhydrochloric acid is then added to about 0.025 mole or more of the distilled vinyl ether, and, while magnetically stirring the solution rapidly, 0.02 mole of sesamol is added thereto in small portions, allowing each portion to dissolve be fore the next addition, this total addition requiring from 10 to 15 minutes. The addition of the .vinyl ether to sesamol plus acid gives resins. The solution is then heated for about 30 minutes at C., or allowed to stand for several hours. To the resulting solution is then added ml. ether and it is then washed twice with 10-20 ml. portions of 0.5 N potassium hydroxide to remove unreacted'sesamol and with 'saturatedsalt solution, all washings being discarded. The other solution is ,dried over sodium sulfate,filtered, evaporated, and distilled. Yields were usually 'or better except for the p-dioxane compound which yielded only 35%.

The foregoing procedure was satisfactorily employed to produce acetals of the formula" wherein R is methyl, and R is ethyl, n -butyl, isobutyl, hyl e yl, et oxye yl -n-but ye hy -nethoxyetl10Xy)ethyl, and 2-chlorethyl, by reacting the corresponding vinyl ether with sesamol. The compound, 2-(3,4-methylenedioxyphenoxy)dioxane was prepared from p-dioxene and sesamol.

2 (2 butoxyethoxy)ethyl 3,4 methylenedioxyphenyl acetal was prepared by adding 1.5 grams of 2;ch loroethyl 3,4-methylenedioxyphenyl acetal to a solution of 0.2 gram sodium in 4 grams of 2-n-butoxyethanol. After heating for 2 /2 hours at in a sealed tube, the product was taken up in ether and worked up in the same manneras the acetals prepared from the vinyl ethers'.

Methylene bis(3,4-methylenedioxphenoxy) is prepared by refluxing an alcohol solution of methylene'iodide, potassium hydroxide, and sesamol in a molar ratio of 1:2:2. Water is added and the product crystallized from ether.

2 ethoxy 5 (3,4 methylenedioxyphenoxy)tetrahydrofuran is prepared by adding a small drop of concentrated hydrochloric acid to 0.025 mole of 2,5-diethoxytetrahydrofuran maintained at 80 while dry nitrogen stirs the solution To the solut on i g adual y added 0 11 0 Q sesamol and th solut on maintained at 0 f r an add t o 2.! hou s. It i then. coole eth a d d. and. worked unin thesame manne as the ase ls Prepared. t e viny ethersr The preparation and some of the properties, of the foregoing compounds are summarized and tabulated as Examples 1 to 12, inclusive, in the following Table I:

acid, then with Water, and twice similarly 3,4-Methylenedloxyphenyl acetal where: Carbon Hydrogen Retr. Ex. Empirical forindex n. Yrepared from sesamol No. mule or M. P plus- R1 is- R: is Galcd. Found Oalcd. Found 15.),

1 methyl ethyl 0, 11, 0 62.8 62. 64 6. 71 8. 78 1. 5060 ethyl vinyl ether.

n-butyl.-- 0 11 04 65. 5 65. 65 7. 61 7. 46 1. 4970 n-butyl vinyl ether. isobutyl C I-[ 04 65. 5 65. 62 7. 61 7. 64 1. 4964 lsobutyl vinyl ether. Z-ethylhexyl 0 1E 0; 69. 4 69. 26 8. 91 8. 86 1. 4911 2ethylhexyl vinyl ether. 2-methoxyethyl C HnOi 60.0 59. 74 6. 71 6. 56 1.5058 2-methoxyethyl vtnyl ether. 2-n-butoxyethyl C H Or 63. 8 63. 58 7. 85 7. 77 1. 4940 2-butoxyethyl vinyl ether. 2-(2-n-ethoxyethoxy)ethy (3 1 11306 60. 3 60. 35 7. 43 7. 17 1. 4938 2(2ggthoxyethoxy)ethyl vinyl e er. 2-(2 n-butoxyethoxy)ethyl OHHMOQ 62. 6 1 (61. 27) 8. 03 7. 92 1. 4908 see method in text. 0 2-chloroethyl 0 135 0401 54. 0 53. 80 6. 35 5. l9 1. 5236 2-chloroethyl vinyl ether. 10 hydrogen.- 3,4-methylenedioxyphenyL. 01 E 10; 62. 5 62. 71 4. 4. 28 2 121-122 methylene iodide.

Heteroeyclic-type acetal 11 2-(3,4-methylenedioxyphenoxy)dloxane..-.. 011111 05 58. 9 58.67 5. 39 5.19 2 75. 5-76. 6 p-dioxene. l2 2-5213? a5!-3,4-methylonedioxyphenoxy) CuHmDs 61.9 62.20 6. 40 6.15 1.5185 2,5diethoxytetrahydrofuran.

e r y o uran.

1 Carbon analysis was low, probably due to the presence 0! formed side reaction material not readily removed.

1 From ether.

I have found further that the acetals of this invention act as synergists for pyrethrins and pyrethrin-type compounds such as allethrin. The synergistic results obtained with some of these acetals are shown in the data in the following Table II, the examples being numbered therein to correspond with the example numbers of Table I.

In the entomological procedure on which these data are based, the turntable method was employed, 100 houseflies per test being used, and in the pyrethrins and allethrin test solutions used against the houseflies refined kerosene was used as the common solvent for the synergist and the respective pyrethrins and allethrin, acetone being added when necessary to increase the solubility of the synergist.

The pyrethn'ns test solutions each'contained a total of 10 mg. of synergist and 1 mg. of pyrethrins per ml. of solvent and the allethrin test solutions each contained a total of 5 mg. of synergist and .5 mg. of allethr'in per ml.

of solvent. The percent mortality of houseflies in 24 hours using these test solutions is listed in Table II.

Table II 3,4-Methylenedioxyphenyl acetal Percent Percent wherein: Mortal- Mortal- Ex No. ity Pyity Alretllrins lethrin R1 is R2 is Test 80- Test Solution lution ethyl 84 92 n-butyl- 74 r 83 isobuty 76 87 2ethylhex 69 91 2-n-butoxyeth 99 99 2-(2-n-butoxyethoxy)ethyl 100 100 9..-.-- 2-chloroethyl 90 93 Heterocyclie type acetals 10 2(3,4-methylenedjoxyphenoxy)dioxane. 100 97 11..-- 2-ethoxy-5-(3,4-methylenedloxyphen- 100 98 oxyltetrahydroiuran. i

Concentration: Percent mortality 1.5 43 2.3 56 3.4 67 5.1 84 7.6 96

Allethrin alone, that is, without added synergist, gave the following mortalities of housefiies in 24 hours, at the recited concentration in mg. per ml. of solvent:

Concentration: Percent mortality .39 39 .59 52 .84 82 1.3 94 2.0 95

in which R is a member selected from the group consisting of an alkyl radical containing 2 to 8 carbon atoms, alkoxyethyl and alkoxyethoxyethyl radicals wherein the alkoxy group contains 1 to 4 carbon atoms, and a chloroethyl radical, comprising reacting the corresponding vinyl ether with sesamol in the presence of a mineral acid catalyst.

2. The process of claim 1 wherein the vinyl other is Z-n-butoxyethyl vinyl ether.

3. The process of claim 1 wherein the vinyl ether is 2- (Z-methoxyethoxy) ethyl vinyl ether.

References Cited in the file of this patent UNITED STATES PATENTS La Forge June 3, 1947 Hedenburg Jan. 5, 1954 OTHER REFERENCES Drukker et al.: Rec. Trav. Chem. 70, pp. 29-34 (1951) Parham et al.: J. A. C. S. 70, pp. 4187-9 (1948). Prell et al.: Chem. Abst, vol. 41, p. 7041 (1947). 

1. A PROCESS OF PREPARING A COMPOUND OF THE FORMULA 